Technical Abstract:
The chloroplast ATP synthase is composed of the integral membrane protein complex, CF0, and the peripheral membrane protein complex, CF1. The light-dependent regulation of ATP synthase activity is carried out in part through redox modulation of a cysteine bridge in CF1 gamma-subunit. In order to further investigate the significance of the regulatory domain as well as the physiological significance of redox modulation, four mutations, C199S, C205S, C199S/C205S, and a deletion of the full redox sensitive domain of the gamma subunit were generated in the the wild type Arabidopsis plants. The expression levels of transgenes and original genes in T0 plants were identified by RT-PCR. The results showed the transgenes were overexpressed behind a constitutive 35S promoter, and remarkably that the endogenous gamma-subunit gene was fully suppressed, indicating that gamma-subunits in ATP synthase of transgenic-plants originated predominately from the transgenes. Measurement of the Delta A 518 revealed that the relaxation kinetics of the dark-adapted transgenic plants were significantly more rapid than that of the wild type. All of the mutations that altered or removed the redox active domain of the gamma subunit prevented the suppression of ATP syntase activity normally associated with disulfide bond in the dark.